An electronic device may be provided with camera means. Such electronic devices may comprise mobile communication devices or terminals, such as user equipment (UE), a mobile station (MS), a cellular phone, a personal digital assistant (PDA) and so on, or other electronic devices, such as a digital camera, a camcorder or a laptop computer.
Camera means are typically provided with a lens element with an adjustable focus and zoom, which may call for an automated and motorised drive of the focus and zoom. Camera means for small devices, such as portable or mobile devices, may need to be very small in size. In particular, very small camera means may be needed for mobile communication devices, in which camera means is only one of a plurality of functions.
Movement resolution and movement range may set requirements for the system. For example, the movement resolution for focus may be very fine, figures of less than 100 μm have been discussed. However, the movement range of the focus may be quite small, for example in the region of maximum 0.5 mm. Zoom typically has very different requirements, such as less accuracy and much more movement range, such as several millimetres.
Patent Application US 2003/0227559 A1 relates to a mechanism for moving lens elements of an electronic camera. The mechanism comprises a support tube and a lens tube, which holds a lens and is mounted coaxially within the support tube. The lens tube is adjustable. Piezoelectric elements are mounted on a flexible circuit board on an outer periphery of the support tube. A piezoelectric element is in a form of a beam and has an attachment lever extending outward transverse to the longitudinal axis of the beam. The piezoelectric element is excited to cause the attachment lever to engage the lens tube and adjust an axial position of the lens tube.
Patent Application WO 2004/047192 relates to an electro-active actuator comprising layers of electro-active material and electrode layers for activation of the electro-active material. The electro-active actuator is a curved strip and has at least one flat portion for providing contact terminal for electrodes.
Patent Application WO 2004/095596 relates to a device comprising a plurality of electro-active benders in an arrangement in which the displacements of individual benders, on activation, contribute to an overall, relative displacement between a proximal end and a distal end of the device.
Patent Application WO 03/061276 relates to a camera with an adjustable focus. The camera comprises a fixed lens, a sensor and a piezo-element positioned under the sensor for displacing the sensor.
In above systems, movement may be limited, in particular for piezoelectric materials, which typically move in a range of approximately three percent of their width. Therefore, for a thin block of material, the movement may be insufficient. Furthermore, solutions may require too much space for implementing in a small device, such as a portable device. Or, solutions may require intricate hand assembly.
Therefore, alternative solutions of an adjustable lens element may be needed. It might be desired to provide camera means with small lens element yet having a sufficient movement range and resolution. Such a lens element may be usable in electronic devices, in particular in portable or mobile electronic devices.